/Engine/Source/Runtime/MeshDescription/Public/MeshDescription.h
Return the vertex instance which corresponds to the given vertex on the given polygon, or INDEX_NONE
[FVertexInstanceID](API\Runtime\MeshDescription\FVertexInstanceID) GetVertexInstanceForPolygonVertex ( const [FPolygonID](API\Runtime\MeshDescription\FPolygonID) PolygonID, const [FVertexID](API\Runtime\MeshDescription\FVertexID) VertexID ) const